1. Field of the Invention
The present invention relates to a write once disc, and more particularly, to a write once disc which allows allocation of an area storing data other than user data, a method of managing a data area of the write once disc, an apparatus recording data in the write once disc, and a method and apparatus reproducing data from the write once disc.
2. Description of the Related Art
Defect management is performed to allow a user to rewrite user data of a portion of a user data area in which a defect occurs to a new portion of the user data area of a disc, thereby compensating for a loss in data caused by the defect. In general, defect management is performed using linear replacement or slipping replacement methods. In the linear replacement method, a user data area in which a defect occurs is replaced with a spare data area having no defects. In the slipping replacement method, a user data area having a defect is slipped to use the next user data area having no defects.
Both linear replacement and slipping replacement methods are applicable only to discs such as a DVD-RAM/RW on which data can be repeatedly recorded and recording can be performed using a random access method.
Meanwhile, methods of disc defect management even on a write once disc on which rewriting of data is not allowed, using the linear replacement method have been developed.
However, there are cases where disc defect management cannot be performed on a write once disc with a recording/reproducing apparatus, using the linear replacement method. For instance, when data is recorded on the write once disc in real time, it is difficult to perform disc defect management thereon with the recording/reproducing apparatus, using the linear replacement method.
For this reason, a spare area is allocated to a write once disc only when disc defect management using the recording/reproducing apparatus is required. That is, the allocation of the spare area is determined by a user's intention.
Also, it is possible to allocate not only spare areas but also other areas to a data area of the write once disc for disc defect management, if necessary.
However, when other areas, not for user data, are allocated to the data area, the recording/reproducing apparatus is not capable of recognizing the structure of the data area.
In other words, if the write once disc contains no information regarding the data area structure, the recording/reproducing apparatus is not capable of determining whether other areas for information other than user data are allocated to the data area or not, and determining the position and size of a user data area when the other areas are formed.
After a write operation, information that specifies areas containing data is written in a bit map format to a predetermined area of a disc, thereby enabling facilitation of a further write operation or a read operation.
More specifically, a recordable area of a disc consists of a plurality of clusters that are data recording units or error correction units. If clusters containing data and blank clusters are recorded as information in the bit map format, the recording/reproducing apparatus can readily access a desired area during a write or read operation.
In particular, bit map information specifying areas containing data is very useful when using a write once disc. In other words, it is required to fast detect a cluster next to a cluster in which data is most recently recorded so as to write data to the write once disc. The bit map information enables fast detection of the next cluster.
Also, it is possible to check a change in the recording state of a write once disc and detect the original data recorded before the change occurs, using the bit map information. The disc recording state may change by recording further data to the write once disc containing data.